Sender Policy Framework (SPF) records allow domain owners to publish a list of IP addresses or subnets that are authorized to send email on their behalf. The goal is to reduce the amount of spam and fraud by making it much harder for malicious senders to disguise their identity.We recommend customers add a SPF rule to their domain name(s) to combat spam

And to assist we have the following predefined rules which will whitelist our servers accordingly. This will make it easier for you to deploy a SPF rule on your domain where you wish to use our services for sending email.